Coding Interview Questions

Ahmed A. - "Good Question, but I would've marked this as medium not hard difficulty, since it's just a straightforward traversal."See full answer

Arshad P. - "Schema is wrong - id from product is mapped to id from transactions, id from product should point to product_id in transcations table"See full answer

Jayveer S. - "WITH suspicious_transactions AS ( SELECT c.first_name, c.last_name, t.receipt_number, COUNT(t.receiptnumber) OVER (PARTITION BY c.customerid) AS noofoffences FROM customers c JOIN transactions t ON c.customerid = t.customerid WHERE t.receipt_number LIKE '%999%' OR t.receipt_number LIKE '%1234%' OR t.receipt_number LIKE '%XYZ%' ) SELECT first_name, last_name, receipt_number, noofoffences FROM suspicious_transactions WHERE noofoffences >= 2;"See full answer

Alina G. - "SELECT upsellcampaignid, COUNT(DISTINCT trans.userid) AS eligibleusers FROM campaign JOIN "transaction" AS trans ON transactiondate BETWEEN datestart AND date_end JOIN user ON trans.userid = user.userid WHERE iseligibleforupsellcampaign = 1 GROUP BY upsellcampaignid `"See full answer

Derrick M. - "SELECT d.departmentname,SUM(o.orderamount) AS total_revenue FROM orders o JOIN departments d ON d.departmentid =o.departmentid WHERE o.orderdate >= CURRENTDATE - INTERVAL '12 months' GROUP BY d.department_name ORDER BY total_revenue DESC; `"See full answer

Gowtami K. - "select DISTINCT p.product_id, p.product_name , CASE when sale_date is null then 'Not Sold' else 'Sold' END as sale_status from products p left join sales s on p.productid= s.productid `"See full answer

Steven S. - "too many questions for clarification on this to start"See full answer

Harshi B. - "SELECT DISTINCT title, ROUND(AVG(rating) over (partition by title),1) avg_rating, ROUND(AVG(rating) over (partition by genre),1) genre_rating FROM rating r JOIN movie m ON r.movieid=m.movieid ORDER by 1"See full answer

Divya R. - "static boolean sudokuSolve(char board) { return sudokuSolve(board, 0, 0); } static boolean sudokuSolve(char board, int r, int c) { if(c>=board[0].length) { r=r+1; c=0; } if(r>=board.length) return true; if(boardr=='.') { for(int num=1; num<=9; num++) { boardr=(char)('0' + num); if(isValidPosition(board, r, c)) { if(sudokuSolve(board, r, c+1)) return true; } boardr='.'; } } else { return sudokuSolve(board, r, c+1); } return false; } static boolean isValidPosition(char b"See full answer

Tiago R. - "function permute(nums) { if (nums.length <= 1) { return [nums]; } const prevPermutations = permute(nums.slice(0, nums.length-1)); const currentNum = nums[nums.length-1]; const permutations = new Set(); for (let prev of prevPermutations) { for (let i=0; i < prev.length; i++) { permutations.add([...prev.slice(0, i), currentNum, ...prev.slice(i)]); } permutations.add([...prev, currentNum]); } return [...permutations]"See full answer

Lucas G. - "SELECT COUNT(*) unique_conversations FROM messenger_sends WHERE senderid < receiverid"See full answer

Tiago R. - "function getDifferentNumberImmutable(arr) { const exists = new Array(arr.length).fill(false); for (let item of arr) { exists[item] = true; } for (let i=0; i < exists.length; i++) { if (!exists[i]) { return i; } } return arr.length; } function getDifferentNumber(arr) { let i=0; while (i < arr.length) { while (arr[i] < arr.length && arr[i] !== i) { // switch (arr[i] and arr[arr[i]]) const j = arr[i]; const temp = arr[j]; arr[j]"See full answer

Anonymous Roadrunner - "from typing import List def traprainwater(height: List[int]) -> int: if not height: return 0 l, r = 0, len(height) - 1 leftMax, rightMax = height[l], height[r] res = 0 while l < r: if leftMax < rightMax: l += 1 leftMax = max(leftMax, height[l]) res += leftMax - height[l] else: r -= 1 rightMax = max(rightMax, height[r]) "See full answer

Richard W. - "static HashMap flattenDictionary(HashMap dict) { HashMap flatDict = new HashMap(); flattenDictionaryHelper("", dict, flatDict); return flatDict; } static void flattenDictionaryHelper(String initalKey, HashMap dict, HashMap flatDict) { for(Map.Entry entry : dict.entrySet()) { String key = entry.getKey(); Object value = entry.getValue(); String ne"See full answer

Gabriele G. - "Using a DFS approach, computing all the distances from typing import List from collections import deque def shortestCellPath(grid: List[List[int]], sr: int, sc: int, tr: int, tc: int) -> int: if sr == tr and sc == tc: return 0 nRows = len(grid) nCols = len(grid[0]) distances = [] stack = deque([(sr, sc, 0)]) visitedSet = set() while stack: nodeR, nodeC, nodeDist = stack.pop() if gridnodeR == 0 or (nodeR, nodeC) in visited"See full answer

E L. - "WITH CTE AS ( SELECT *, ROWNUMBER()OVER(PARTITION BY utxoid ORDER BY transactionid) AS trxrk FROM transactions JOIN transaction_inputs USING (transaction_id) JOIN utxo USING (utxo_id) ) SELECT transaction_id AS InvalidTransactionId FROM CTE WHERE sender!=address OR trx_rk > 1 `"See full answer

Erjan G. - "this task is misleading . i used lag(1) and lead(1) cuz it did not say "compare temperature from 2 days before and 1 day before" , it reads to me as if its asking "compare cur temperature to prev and future and see if it rose and fall""See full answer

Vince S. - "func isMatch(text: String, pattern: String) -> Bool { // Convert strings to arrays for easier indexing let s = Array(text.characters) let p = Array(pattern.characters) guard !s.isEmpty && !p.isEmpty else { return true } // Create DP table: dpi represents if s[0...i-1] matches p[0...j-1] var dp = Array(repeating: Array(repeating: false, count: p.count + 1), count: s.count + 1) // Empty pattern matches empty string dp[0]["See full answer

Gowtami K. - "with cte as (select *, row_number() over(order by score desc) as rn from players) select player_name, score, rn as ranking from cte where rn= 4 or rn =6 or rn =11 `"See full answer